Generally, in the field of the clinical chemistry, measurement of physiologically active substances in such organism samples as serum, urine or tissue fluid, e.g., enzymes, lipid, protein, etc., is made widely for the purpose of diagnosis of diseases and grasping disease conditions.
Automatic analyzers have various features such as quick operation, high efficiency, high accuracy, convenient handling, small amounts of samples and reagent required for analysis and capability of saving energy, so that they are employed widely in the field noted above. The measurement is usually done in the order of taking a sample, adding a reagent, mixing, incubation, color comparison (measurement of absorbance) and calculation. Of these, the incubation is effected by an air bath system, a water bath system or oil bath system. Among them, most generally a water bath is used as thermostat bath. The reaction temperature is usually below 50° C. and most generally 37° C. The absorbance is measured by a system in which measurement is done by sucking up reaction solution from a reaction vessel to a cell, or a system in which the reaction vessel is measured directly as measurement cell. At present, the latter system is mainly adopted. In the measurement of this system with a water bath as thermostatic water bath, light from a light source disposed outside the water bath is passed through the water bath and through a reaction vessel therein to be detected by a sensor disposed on the opposite side of the water bath. In this way, the reaction vessel is also used as cell for measuring. The wavelength used for measurement is usually 340 to 900 nm.
Usually, water in the thermostatic water bath in the automatic analyzer is replaced once or several times a day. At the time of water replacement, air bubbles are frequently attached to the outer wall of the reaction vessel. To prevent this, a slight amount of cleaner is usually added. The cleaner used to this end is usually prepared from various surface active agents as main component by adding a chelating agent, a pH controller, a preservative agent, etc. to the main component. It has poor bubble-formation property, and it is added to a concentration of 0.05 to 2.0 w/w % in the water bath. However, in the water bath using water in the thermostatic water bath containing such a cleaner, the component of cleaner serves as source of nutrition to promote generation of algae and growth of various microorganisms (bacteria etc.) in the use of long time running (Any preservative agent added can not substantially provide any effect). In consequence, a great error in the measurement of the absorbance was produced by a cause such as generation of algae on the reaction vessel and/or increase in turbidity in water in the thermostatic water bath, etc. For this reason, as the analyzer requires sufficient daily maintenance control in the use of the apparatus, a great deal of labor is required for accuracy maintenance and maintenance control by frequently monitoring or periodically cleaning the inside of the water bath. Thus, although addition of a cleaner to a thermostatic water bath is necessary and effective, sufficient daily maintenance control is required to be done, therefore, improvement in this respect is strongly desired.
The present inventors thought that a cause for generation of algae and growth of microorganisms (bacteria etc.) is that the final concentration of the preservative agent present as a component of the cleaner in the thermostatic water bath is less than an effective concentration in the case of ordinary concentration of the cleaner (which is 0.05 to 2.0 v/v %). Accordingly, the present inventors considered that triazine derivatives which were effective in small quantity, that is, low effective concentration preservative agents were suitable for a preservative agent as a component of the cleaner. And after intensive researches and investigations, the present inventors found that, it is possible to prevent generation of algae and growth of microorganisms (bacteria etc.) in the thermostatic water bath by using a cleaner containing a triazine derivative and a surface active agent, and filed it as a patent application (Patent Document 1).
However, it was found that although the cleaner having the composition noted above permits prevention of the generation of algae and growth of microorganisms (bacteria etc.) in the thermostatic water bath for a long time, but when the liquid concentrate of the cleaner is preserved at a high temperature, some of its components are decomposed with a lapse of time, thus producing substances which have absorption in a wavelength range of 300 to 900 nm used for the measurement and are liable to cause great errors in the absorbance measurement.
Therefore, the present inventors further conducted intensive investigations, and have found that the cleaner obtained by adding a compound represented by the following formula [A]:
[wherein R9, R10, R11 and R12 are independently an a hydrogen atom, a methyl group or a hydroxymethyl group, and n is an integer of 1 to 5] to a cleaner composed of a triazine derivative as low effective concentration of a preservative agent and a surface active agent can prevent not only the generation of algae and growth of microorganisms (bacteria etc.) in the thermostatic water bath, but also restrain formation of a substance having absorption in the measurement wavelength range (300 to 900 nm) as a result of decomposition of a component of the cleaner when the cleaner is preserved at a high temperature. This invention also is already filed as a patent application (Patent Document 2).
On the other hand, for prevention of nosocomial infection by various types of bacteria (for example, Pseudomonas aeruginosa, Staphylococcus aureus, etc.), various kinds of pretreatment are sometimes demanded. Although no example is reported that a cause of such infection is a thermostatic water bath in an automatic analyzer, there are some thoughts that prevention at a pre-stage is necessary, and there are some opinions to desire development of a cleaner having stronger germicidal effect than conventional cleaners.
[Patent Document 1] JP-A-1-40599
[Patent Document 2] JP-A-1-319407